textproduct: Albany

WHAT HAS CHANGED

Frost/Freeze headlines have ended for this morning. Updated first key message to reflect current forecast.

KEY MESSAGES

1) Some patchy frost can't be ruled out tonight in the southern Adirodnacks.

2) Widespread rain expected Saturday afternoon into Sunday, although the start time on Saturday remains somewhat uncertain. Rainfall amounts will range from around 0.5 to 1.5 inches, which is not expected to lead to any flooding.

DISCUSSION

KEY MESSAGE 1...Today and tonight, the sfc high moves overhead then slides off to the northeast. With confluent upper flow aloft and the high nearby, large-scale subsidence should keep up completely dry with just some high clouds around. It will be a nice day with low humidity and highs in the 60s to around 70 for valley areas south of Albany. Depending on how quickly high clouds increase tonight, temperatures across northern / northeastern zones may be able to radiate efficiently enough for temperatures to drop into the 30s again. While confidence is still somewhat low due to uncertainty in how quickly the thicker high clouds arrive, we can't rule out some patchy frost across interior Hamilton and Warren Counties. Have collaborated with WFO BTV to hold off on any additional headlines for the time being, though, given this uncertainty.

KEY MESSAGE 2...Saturday, upper ridging will be amplifying overhead while a negatively tilted upper shortwave embedded within a larger-scale trough tracks along the upstream side of the ridge. At the sfc, associated primary sfc low will track to our west towards the Great Lakes, with a secondary coastal low developing Saturday night/Sunday. Strengthening southeasterly LLJ to around 45 kt will aid in moisture transport into our region, with PWATs climbing to 1-1.25" Saturday afternoon into Sunday night. This moisture will overlap with a band of sloping FGEN and low to mid-level isentropic lift, so there is high confidence for a period of rain Saturday into Sunday.

The big question is how early rain begins Saturday. With strong upper confluence and very dry low to mid-level air in place ahead of the advancing rain shield, we have leaned towards the slower side of guidance with bringing the rain in Saturday. Rain could begin as early as the late morning across the southern Catskills, but for areas north and east of the Capital District rain may very well hold off until Saturday evening after dark. Most of the uncertainty seems to be tied to the southwestward extent of an upper shortwave tracking across Maine/Nova Scotia Saturday morning and the degree to which the confluence aloft strengthens behind it. Guidance still seems to be struggling with this somewhat, likely due to the small wavelength of this feature, so additional adjustments to timing of rain Saturday may still be possible with future forecasts. Temperatures will vary widely across the region Saturday, with 50s for southwestern areas that see more rain to mid and upper 60s further north and east where filtered sun will be possible through much of the day.

High confidence for rain to overspread the rest of the region Saturday night as the better mid-level warm advection/isentropic lift reaches the area, with showers lingering through much if not all of the day Sunday. Sunday looks quite chilly, and we lowered temperatures significantly from the NBM with widespread clouds/rain. Current forecast highs are for 40s in the high terrain to mid 50s for valley areas, and these temps may even be generous. Showers taper off Sunday evening. Rainfall amounts look to range from around or just under a half inch for northeastern areas to up to around an inch and a half near our southwestern CWA border with BGM and OKX. With a steady light to occasionally moderate stratiform rain and little to no instability, rainfall rates look too light for any short-fuse hydro concerns, and overall rainfall amounts look too low for any flood concerns now that we are mostly greened-up. In fact, this rainfall will be quite beneficial with many places across the region having not seen any rain in the last 5-7 days.

While a brief break in the showers is expected Sunday evening/early Sunday night, it looks like a southern stream shortwave will phase with a northern stream disturbance over the Ohio Valley Sunday night, tracking over our region late Sunday night into Memorial day. This will be accompanied by another surge of moisture and additional showers. Monday morning is now looking on the wetter side, although shower chances will decrease through the afternoon. Best chance for showers will be across our southern areas, but latest 00z guidance has trended wetter for the region as a whole. Monday will at least be warmer, with temperatures in the 60s (terrain) to low 70s (valleys) expected at this time.

Drier weather returns Tuesday through the middle of next week. Initially zonal flow becomes more amplified and northwesterly as upper ridging builds over the center of the country. This will put us back into a drier pattern. While the NBM/WPC long term forecast is showing temperatures reaching the mid 80s both Tuesday and Wednesday next week, this is well above MOS guidance and seems to be at least a few to several degrees too warm given the upper ridge axis remains several hundred miles west of our region. Upper 70s to possibly low 80s in the Mid Hudson Valley seems more reasonable for mid-week highs, with the drying pattern allowing for overnight lows in the 40s to 50s each night.

AVIATION /13Z FRIDAY THROUGH TUESDAY/

Through 12Z/Sat...VFR conditions are expected through the upcoming TAF period. High pressure will build over the region bringing nothing more than some passing high clouds at times, with thickening high/mid level clouds tonight. Winds will be mainly north to northeast at less than 8 KT through mid morning, then east to northeast at 5-10 KT later this morning through afternoon. Winds will then become light/variable around and after sunset.

Outlook...

Saturday Night: High Operational Impact. Definite RA. Sunday: High Operational Impact. Definite SHRA...RA. Sunday Night: Moderate Operational Impact. Chance of SHRA. Memorial Day: Moderate Operational Impact. Chance of SHRA. Monday Night: No Operational Impact. NO SIG WX. Tuesday: No Operational Impact. NO SIG WX. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: Low Operational Impact. Slight Chance of SHRA...TSRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.